According to a related art, the case where a call is made from a mobile telephone which is one kind of wireless telephone to another mobile telephone or a fixed telephone and the like, the calling mobile telephone generates a tone corresponding to the operating state of the called telephone. For example, in the case where the calling mobile telephone is calling the called telephone, the calling mobile telephone generates a ring back tone. In the case where the called telephone is busy, the calling mobile telephone generates a busy tone. In addition, in the case where the called telephone is a mobile telephone and exists out of a service area, the calling mobile telephone generates a voice such as “the telephone you calls is turned off or is in a place radio waves do not reach”.
This operating state of the called telephone is generated in the calling mobile telephone by transmitting tone data generally registered in a network system such as an automobile switching center to the calling mobile telephone (refer to, for example, Japanese Patent Laid-Open No. Hei 10-313485).
More specifically, in the case where the called telephone receives an incoming call from the calling mobile telephone, the called telephone transmits call setting accepted data corresponding to its operating state at that time to the network system. The network system, when it receives this call setting accepted data, reads tone data corresponding to the operating state of the called telephone from the registered data on the basis of the call setting accepted data, and transmits the tone data to the calling mobile telephone. The calling mobile telephone generates a tone corresponding to this received tone data.
In this manner, the tone data corresponding to the operating state of the called telephone (operating state informing data) is registered in the network system, so that only a system operator can generate and change the tone data. This leads to the problem that a user cannot be informed of the operating state of the called telephone in the user's original representation form.